Cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (HIPEC) versus palliative chemotherapy for peritoneal metastasized gastric cancer: a propensity score matched analysis.

INTRODUCTION

The role of cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) in gastric cancer patients with peritoneal metastases (PM) and a low peritoneal cancer index (PCI) remains debated. We compared real-world overall survival (OS) between induction chemotherapy followed by CRS with HIPEC versus palliative chemotherapy-only in gastric cancer patients with peritoneal metastases (PM).

METHODS

This retrospective, international multicenter cohort study analyzed gastric cancer patients with synchronous PM (cT1-4N0-3M1) treated with induction chemotherapy and CRS + HIPEC (UZ Ghent/UZ Leuven) versus palliative chemotherapy-only (nationwide Netherlands Cancer Registry). The primary outcome was OS for PCI≤12. Secondary outcomes were OS for patient subgroups with PCI≤6, and PCI 7-12. Covariate adjustment and 1:1 propensity-score-matching (PSM) addressed baseline differences. Survival was analyzed using the Kaplan-Meier method and Cox proportional hazards models with hazard ratios (HR).

RESULTS

Between 2009 and 2022, 233 patients with PCI≤12 were included. Patients treated with CRS + HIPEC (n = 52) had a significantly higher OS after covariate adjustment (HR 0.40; 95% CI 0.26-0.63, p < 0.001) versus patients treated with chemotherapy-only (n = 181). After 1:1-PSM, for PCI≤12 (n = 82), median OS was 23.5 months (CRS + HIPEC) versus 11.8 (chemotherapy-only) (HR 0.30; 95% CI 0.17-0.54, p < 0.001). After 1:1 PSM for patient subgroups with PCI≤6 (n = 58) and PCI 7-12 (n = 20), median OS was 26.4 and 21.8 months (CRS + HIPEC) versus 13.2 and 12.0 months (chemotherapy-only) (HR 0.27; 95% CI 0.14-0.52, p < 0.001, and HR 0.32; 95% CI 0.11-0.92, p = 0.034).

CONCLUSIONS

in this retrospective PSM-cohort CRS + HIPEC was associated with a clinically meaningful higher OS in gastric cancer patients with limited PM compared to chemotherapy-only, supporting its potential.